A dust collector is a common household cleaning device and has a function of separating dust and debris from air. At present, a filter device is the most common and most effective solution of realizing separation of air and dust. The filter device often needs to be disassembled from inside of the dust collector in a using process. For example, a great deal of dust will be accumulated on the filter device after the dust collector is used for a period of time, the filter device needs to be installed again after being disassembled and cleaned, or is replaced by a new filter. An easily-disassembled filter is matched with a dust filter fence with a middle column, and is a more practical filter device. A patent (Publication No.: CN101711657) discloses a replaceable filter device, which includes a filter device bracket (i.e., a filter cage), wherein a filter is sleeved on the bracket and penetrates through an end cap with an elastic material at one end of the filter device, the end cap is provided with an end hole, a supporting column (a middle column) on the bracket penetrates through the end hole when the filter device is installed, and the end hole is kept within an area where an outer diameter of the supporting column is smaller. A patent (Publication No.: CN203328636) discloses a replaceable filter device, wherein an end cap is provided with an end hole penetrating through the end cap, a middle column on a filter bracket penetrates through the end hole, a fixing button is in thread connection to the end cap, the fixing button is provided with a plurality of claw parts in an integral extending manner, and the claw parts on the fixing button are propped open by the middle column in the process that the fixing button is in thread connection to the end cap, so that the claw parts generate greater force to the middle column to lock the middle column. A patent (Publication No.: U.S. Pat. No. 5,783,086) discloses a replaceable filter device, wherein an end cap is provided with an end hole penetrating through the end cap, a middle column on a filter bracket penetrates through the end hole of the end cap, and a fixing button is in thread connection to the middle column penetrating out of the end hole. The filters in the above solutions can be better matched with the filter cages with the middle columns, and the middle columns of the filter cages can be fast assembled/disassembled and locked. The design provides a novel solution.